LM317 and HC4053 combine to make a PWM power DAC while Q1 forces preregulator U3 to track and maintain a constant 3 V U2 I/O headroom differential to improve efficiency

Download PDF

Other Materials from the Main Document

• Article «Tracking preregulator boosts efficiency of PWM power DAC»
• Figure 1. LM317 and HC4053 combine to make a PWM power DAC while Q1 forces preregulator U3 to track and maintain a constant 3 V U2 I/O headroom differential to improve efficiency
• Figure 2. V_OUT (1.25 V to 12.5 V) versus PWM D (0 to 1) where V_OUT = 1.25 / (1 - 0.9 D)
• Figure 3. The inverse of Figure 2 or, the PWM D required for any given V_OUT, where PWM D = (1.111 - 1.389/V_OUT)